Bone dysplasia is invariably seen in:

Ans. d. Developmental defect Bone dysplasia is invariably seen in developmental defect. Developmental abnormalities of the skeleton are complex, variable, frequently genetically based, and first become manifest during the earliest stages of bone formation. They can be of two types-Dysostoses or Dysplasias.'-Robbins 8/e p1210 Developmental anomalies resulting from localized problems in the migration of mesenchymal cells and their formation of condensations are known as dysostoses. They are usually limited to defined embryologic structures and may result from mutations in ceain transcription factors (Homeobox genes). Mutations in the regulators of skeletal organogenesis, such as cellular signaling mechanisms (e.g., growth factors and their receptors), and matrix components (e.g., types 1 and 2 collagen), affect cailage and bone tissues globally, and these disorders are known as dysplasias.-